The construction of existing liquid crystal display (LCD) is that a liquid crystal cell is placed in two parallel glass substrates, a thin film transistor (TFT) is disposed on the lower substrate glass, a color filter is disposed on the upper substrate glass, the direction of rotation of liquid crystal molecules is controlled by a signal and voltage change on the TFT, so as to achieve the display purpose.
Accompanied by the increasing demand for high-quality small-sized single-chip LCD projectors in the home market, especially to satisfy 1920×1080 (commonly known as 1080P) and 1280×720 (commonly known as 720P) high definition displays whilst taking into account the overall balance between projector volume reduction and performance improvement, 600×1024 and 720×1280 resolution full-color LCDs are generally used as image display devices, and 4 inches, 4.2 inches or 4.3 inches are generally selected as the LCD size. The resolution and size are also specifications commonly used by smart mobile phones, and then have become preferred choices for the design of small home projectors.
Taking a 720P (720×1080) resolution 4, 4.2, or 4.3-inch LCD as an example (same for 600×1024 resolution), the 720P resolution LCD screen itself is a portrait while projection output pictures are landscapes, mobile phone screens commonly use the mobile industry processor interface (MIPI) signal interface to transmit images while commonly used projector video processing chips do not support portrait display and MIPI, which is the problem of this technical solution and constitutes the biggest difficulty of applying the mobile phone screen to small projectors. The existing solution is for use on mobile phones, namely, utilizes the portrait to landscape conversion function of Android-based hardware and software systems, but the cost of software and hardware with an operating system is very high. It is necessary to find an economical and practical solution to implement this image rotation function.